The disclosure relates to a method of fabricating a semiconductor device, and more particularly, to a method of forming a noble metal layer.
Recently, the technology of using noble metal layers including ruthenium (Ru) or Iridium (Ir) layers as the electrode material in a dynamic random access memory (DRAM) or ferroelectric random access memory (FeRAM) has been introduced.
Noble metal layers including ruthenium and iridium layers are formed using a chemical vapor deposition (CVD) method or an atomic layer deposition (ALD) method. Also, a deposition source that includes an organic metal compound is required. The organic metal compound is often referred to as a precursor.
When using a CVD method or an ALD method to form a noble metal layer, a reaction gas is used to decompose the organic metal compound. The reaction gas often includes oxygen (O2), hydrogen (H2), and ammonia (NH3).
When using ammonia or hydrogen as a reaction gas, reactivity is quite low and thus, to obtain proper deposition results, the deposition temperature is often raised to approximately 500° C. or higher. Even if a plasma is used, the deposition rate is still quite low. In particular, when forming a noble metal layer over a dielectric layer including a zirconium dioxide (ZrO2) layer, characteristics of the dielectric layer formed below the noble metal layer deteriorate due to the high deposition temperature.
In order to improve this limitation, oxygen may be used as a reaction gas because using oxygen allows the deposition process to be performed as a low temperature process.
However, using oxygen as a reaction gas may require a very long incubation time because the substrate dependency is high. When the incubation time is long, the surface of the noble metal layer being formed often becomes very rough and the growth rate is quite slow.
Furthermore, using oxygen as a reaction gas when performing the deposition process at a low temperature may result in a rapidly decreasing deposition rate which, in turn, would deteriorate mass productivity.
Thus, using oxygen, hydrogen, or ammonia for forming a noble metal layer may make it difficult to obtain sufficient adhesive property and mass productivity of the noble metal layer.